We are studying the mechanism of action of different interferons (IFs). Principal emphasis is on the antiviral pathway; studies of the effects of IFs on cell or tumor growth will be limited to demonstrating that the antiviral and cytopathic pathways are disparate. We hope to identify the step or steps at which decay of IF antiviral action occurs during inhibition of the development of the antiviral state, and to continue the collection of data bearing on the interaction of IF and the cell membrane. Studies of the kinetics of synthesis of IF-mediated antiviral proteins are also planned.